Ballistic Coefficients

[wymberley]

As it's pouring down yet again and purely out of sheer boredom had a look at a couple of articles on the Subject.

 

We know manufacturers sometimes tell porkies - or at least we think they might. Well, they do and up to some 25% exaggeration. No names, no pack drill.

 

One little titbit though that may be of interest and/or beneficial: As an approximation, the BC can be estimated as the fraction of 1000 yards over which distance a bullet will lose 50% of its ME. Put another way,a bullet having a BC of 0.300 should lose half of its ME at 300 yards. Might be useful to a reloader trying to figure out how any given load might turn out.

Edited October 9, 2012 by wymberley

[kent]

Bc can be mis stated its also changed by different barrels. Use it as a rough guide to be proved on the range or chrono the bullets at two distances in flight and calculate it if you want to get serious. Personally i only see it as a start point in bullet selection and for forulating my initial dope data

[wymberley]

Bc can be mis stated its also changed by different barrels. Use it as a rough guide to be proved on the range or chrono the bullets at two distances in flight and calculate it if you want to get serious. Personally i only see it as a start point in bullet selection and for forulating my initial dope data

 

Yep, probably why I used words like 'approximation' and 'might'. Thanks for your input though.

[Vipa]

If the BC of a projectile can change depending on the barrel, how can a ballistics calculator work and be accurate, which, the better ones are as they do not know anything about the barrel the projectile is being squeezed through?

[kent]

If the BC of a projectile can change depending on the barrel, how can a ballistics calculator work and be accurate, which, the better ones are as they do not know anything about the barrel the projectile is being squeezed through?

 

I think you answered the question with a statement there. Easy they don't, sure enter near enough the correct BC and you get pretty close. No two shooters will be garanteed to shoot the same zero, using the same gun, same scope, same issued ammo - but they will close enough, its the same with ballistic programs "close enough"

 

 

Now you might doubt what i say here, thats your option but check out the data compilation used by British and other forces snipers. There are sections and sections of "real world data" yep thats the title REAL WORLD DATA in issued log books to complete. Now the MOD are big on saving money on practice ammo so why not just issue all the guys with the data and save a lot of messing about?

[Catweazle]

There are many factors to consider that aren't immediately obvious, such as rifling twist. I think an over-stabilised bullet can have poor BC at longer ranges yet could appear nearly normal at short ranges, it's probably possible to calculate this error but as Kent says the real proof is in the real world.

 

I have no experience of long-range shooting, but the theory is interesting if you have an inner-geek.

[wymberley]

 

Now the MOD are big on saving money on practice ammo so why not just issue all the guys with the data and save a lot of messing about?

 

 

Practice!? Thing of the past.

 

As a chief range warden (albeit retired) on a MoD range, I would imagine that the pass mark for the APWT is still a large jar of Maxwell House for the training team.

[Vipa]

 

 

Practice!? Thing of the past.

 

As a chief range warden (albeit retired) on a MoD range, I would imagine that the pass mark for the APWT is still a large jar of Maxwell House for the training team.

 

I was go smacked recently... One of my friends/clients is current serving RAF... It is years since he was on a live fire range, his firearms testing is all done with toy guns on a cinema simulation range now!!!!

[jimboozle]

Practice!? Thing of the past.

 

As a chief range warden (albeit retired) on a MoD range, I would imagine that the pass mark for the APWT is still a large jar of Maxwell House for the training team.

 

I second that! Although I did earn my marksman qualification fair and square at Sandhurst - dropped 2 shots in the whole test.

 

Quite how anyone could fail an APWT I'm not sure, it's not the most challenging of tests, however the soldiers in my platoon never failed to surprise me!

 

Every soldier in the British Army is required to fire the APWT each year as part of their annual tests - this is also applicable to the Territorial Army. In the infantry this was (obviously) taken very seriously. i took every opportunity I could to get my troops out on the range, often doing live fire & manouvre and other realistic training.

 

I think lip service is paid to shooing in some of the support arms, however at the end of the day, when you get contacted, you need to be able to use your personal weapon effectively.

Edited October 10, 2012 by jimboozle

[wymberley]

I was go smacked recently... One of my friends/clients is current serving RAF... It is years since he was on a live fire range, his firearms testing is all done with toy guns on a cinema simulation range now!!!!

 

There's never anything new. I left the RAF in 1984 and the last time I went to the range was in1966 (kept marksman with 303 and S&W 38 which meant you could hold them still) prior to leaving for Aden. Bit of a white lie though, actually got on the range in 1978 but asked if I could just check the AYA with single slug. Was told yes and having done so was told to push off as, "if you can shoot that you can shoot anything". Good fun afterwards though - they used to get me so shoot big holes in life-ex aircraft in a direction that would cause most internal damage - cables, pipes and control runs, etc - so the guys could be assessed on battle damage repairs.

[jimboozle]

I was go smacked recently... One of my friends/clients is current serving RAF... It is years since he was on a live fire range, his firearms testing is all done with toy guns on a cinema simulation range now!!!!

 

The SAT (small arms trainer) simulator is a pretty good training tool, but no substitute for the real thing. When used correcly, it allows you to check peoples bad habits, you can view the muzzle rise and fall pre-shot, you can view the trigger pressure to see if they are snatching the shot, and check weapon cant and butt pressure.

 

You can also introduce stoppages into the weapon to check peoples stoppage drills.

 

Just pre-iraq, we were using it for rules of engagement situations, there would be a vid of some chaps with rifles, and you had to assess the legality of dropping them. This was an excellent way of sparking debate.

 

However, as stated before, no substitute for live firing and realistic training with live ammunition.

[wymberley]

The SAT (small arms trainer) simulator is a pretty good training tool, but no substitute for the real thing. When used correcly, it allows you to check peoples bad habits, you can view the muzzle rise and fall pre-shot, you can view the trigger pressure to see if they are snatching the shot, and check weapon cant and butt pressure.

 

You can also introduce stoppages into the weapon to check peoples stoppage drills.

 

Just pre-iraq, we were using it for rules of engagement situations, there would be a vid of some chaps with rifles, and you had to assess the legality of dropping them. This was an excellent way of sparking debate.

 

However, as stated before, no substitute for live firing and realistic training with live ammunition.

 

I was allowed to have a go on the one where I worked soon after it was installed. They ran the Irish street seen ambush thingy. I was so amazed at the reality, I forgot what I was supposed to be doing. A ******* popped up from behind a wall and shot me. I have to say that I was convinced that I was dead.

 

(Got him next time though!)